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Multipliers: What We Should Have Known

There’s a very nice interview with Olivier Blanchard, who is leaving the IMF, in which among other things Olivier says the right thing about changing one’s mind:

With respect to outside, the issue I have been struck by is how to indicate a change of views without triggering headlines of “mistakes,’’ “Fund incompetence,’’ and so on. Here, I am thinking of fiscal multipliers. The underestimation of the drag on output from fiscal consolidation was not a “mistake’’ in the way people think of mistakes, e.g., mixing up two cells in an excel sheet. It was based on a substantial amount of prior evidence, but evidence which turned out to be misleading in an environment where interest rates are close to zero and monetary policy cannot offset the negative effects of budget cuts. We got a lot of flak for admitting the underestimation, and I suspect we shall continue to get more flak in the future. But, at the same time, I believe that we, the Fund, substantially increased our credibility, and used better assumptions later on. It was painful, but it was useful.

Indeed. There are a lot of people out there whose idea of a substantive argument is “you used to say X, now you say Y” — never mind the reasons why you changed your view, and whether it was right to do so.It’s important not to fall into the trap of being afraid to let new evidence or analysis speak.

One thing I would say, however, is that on this particular issue the Fund should have known better. Olivier says that the evidence “turned out to be misleading in an environment where interest rates are close to zero and monetary policy cannot offset the negative effects of budget cuts”, but didn’t we know that? I certainly did.

And let me also beat one of my favorite drums: the prediction that multipliers would be much larger in a liquidity trap came out of IS-LMish macro (or, to be fair, New Keynesian models) and has been overwhelmingly confirmed by experience. So this was yet another victory for Keynesian analysis, the success story nobody will believe.